According to one embodiment, a sensor includes a structure body including a deforming portion, and a first sensing element provided at the deforming portion. The first sensing element includes first to fourth magnetic layers and a first intermediate layer. The first magnetic layer is provided between the second and third magnetic layers. The fourth magnetic layer is provided between the first and third magnetic layers. The first intermediate layer is provided between the second and first magnetic layers. The third magnetic layer includes at least one of a first material or a second material. The first material includes at least one selected from the group consisting of Ir—；Mn, Pt—；Mn, Pd—；Pt—；Mn, and Ru—；Rh—；Mn. The second material includes at least one of CoPt, (CoxPt100-x)100-yCry, or FePt. A crystallinity of at least a portion of the fourth magnetic layer is higher than a crystallinity of the first magnetic layer.
